We speculate that the oscillation of blood flow generates shear stress which would develop muscle stress, and the variation of muscle stress induces vasomotion. If so, the variable period of heartbeat should induce the low-frequency component and is independent of the heartbeat curve. The determination of primary variables of fluid flux and average pressure in each cross-section of vascular could predict peak pressures (Daversin-Catty et al., 2021).

It has been noted that the cardiovascular system is not a simple linear system and involves nonlinear contributions (Rajendra Acharya et al., 2006). Moreover, it was found that the oscillating blood flow in microvascular networks exhibited nonlinear behavior (Carr and Lacoin, 2000).

Adding white noise and then stopping would induce an SNR increase in the frequency band related to vasomotion (∼0.1 Hz).

respiration should be included, since blood flow to the skin and respiration are known to interact intensively6.

However, there is evidence that while IM band activity and respiration are closely related processes, they are yet distinct10,43